Example embodiments of the present inventive concepts relate to semiconductor devices and methods of forming semiconductor devices. As integrated circuits are developed, semiconductor devices capable of high speed operation and high integration may be desired. In an attempt to provide high speed operation and high integration, a semiconductor device having a line width of a several tens of nanometers has been developed and commercialized. However, the reduction in critical dimension (CD) of semiconductor devices may result in an increase in electrical resistance of interconnection lines and an increasing capacitive coupling between the interconnection lines, and it may thus be difficult to realize high speed operation of semiconductor devices.